The causes of the shock — that is, why the polls were wrong — won’t be clear until analysts have been able to sort through the returns. There are a few likely suspects: Trump supporters who didn’t admit it to pollsters; a late break of undecided voters moving his way; lower-than-expected turnout among Democrats, both white and non-white; and higher turnout among conservative working-class whites.

In a strange way, the immediate future is clearer than the immediate past: All signs point to a radical shift in federal policy.

Republicans now control the presidency, the Senate, the House and will likely soon control the Supreme Court. Even more important, a radicalized version of Republicanism will likely dominate those institutions.

It’s true that the Senate does not have a 60-vote, filibuster-proof majority. But Senate rules allow a simple majority to pass budget bills, and Republican leaders may weaken the filibuster anyway.

What can the Democrats do about all this? First, they can show the same unity and discipline that Senate Republicans had during the Obama years, albeit to a different end. They can offer to work with Republicans on sensible compromises, especially with Trump, given his uncertain allegiances — and Democrats can outright oppose any partisan bill that hurts ordinary Americans.

Some shrewd observers expect Republicans to have little interest in compromise. The Republican agenda “is going to happen,” Theda Skocpol, a Harvard professor, told me, “and there is nothing Democrats can do to stop it.”

Democrats would then have only one good option: describing what was really happening, clearly and repeatedly.

“Repealing Obamacare” will mean taking health insurance — and, by extension, medical care — from millions of people (including many lower- and middle-income whites). Trump’s proposed tax cut will bestow an average $1.1 million tax cut on the top 0.1 percent of earners. The resulting lack of government funds will rob schools and promising medical research of funding. Rolling back environmental regulations will increase pollution and its adverse effects on health and, most worrisomely, the damage from climate change.

Democrats can’t simply foment during press conferences in the halls of Congress. They need an outside game too, one based in individual states, that provides tangible examples of how these policies will change people’s lives.

A frequent question I heard on Wednesday was, “Are we going to be O.K.?” My simple answer is yes. The country has survived worse. But I don’t want to sugarcoat reality. The immediate future will include a lot of changes that will make life harder for many Americans.